Bookbinding adhesives and a method of applying same



Patented Sept. 30, 1952 BO'OKBINDING ADHESIVES AND 'A METHOD" OF APPLYING SAME- Rodney G; Brown; North Brunswick Township, Middlesex County,-N. J., assignor to E. I. du Pontde Nemours & Company, Wilmington, Deli, a corporati'on'of Delaware No Drawing. Application September 18, 1946, Serial No. 697,823

v 16 Claims. 1,

This invention relates. to the art ofbook-binding, and more particularly to hot melt adhesives fonuse therein.

It will be understood that, where the word bdok'is used"herein, this includesmagazines, pamphlets, writing,v tablets, and similar articles,

as well as books themselves;

The leaves. of books and similar articles of ness, the center pagesflare insecurely bound and) frequentlyfall out; 7 Cheap books'and. pamphlets have also been-made in'wh'ich the leaves are embed'dedl'in'an adhesive, butth'eiadhesi'ves heretofore used are not resistant to attack by molds, are adversely affected byimoisture, and eventually failby. becoming .brittle. Such adhesives have the further disadvantage of varying. greatly in setting speed under conditions Of fluctuating humi dity, resulting in considerable loss of production during the manufacture of books on high speed mechanical equipment.

An object of the present invention is to provide books with an improved and permanent-binding. Another object is the =provisionof a simple and eflicient process for binding the edges or'pagesof paper to form a book; Still another object is the provision of a process which eliminates the the provision of a bookbinding process which:

speeds production and reduces the storage space needed between operational steps in book manufacture. Another object is the provision of a b'ookbindi-ng process which does not limitthe thickness of 'thebook produced. Another object is aim-improved binding medium which does not cause mechanical or chemical; deterioration of thepaper; A further" object is a bindingmedium which is waterprooi, isunafiected by long expo-- sure to moisture and. air, and .;will withstand. severe and numerousflexings. ,A still furtherobject iszthe provision ofa binding medium which 2 is tough and flexible at highand-lo'w temperatures.- Other objectswillb'ecome apparent as-the description proceeds.

These objects are accomplished by applyinga permanently flexible, waterproof; tough, thermoplastic adhesive composition to the bindingedges of a plurality of paper sheets to form a'stron'g', adhesive, continuous film over the entire surface of these edges and with good penetration of the interstices between the fibers at the paper'edges, a's'well as between the individual sheets, thus contributing to the greater overall strengtfiof the binding.

In the preferredembodiment"of'the invention the thermoplastic adhesive composition" com prises a hydrous ethanol soluble polyamide and a compatible liquefying softener and is applied in .tWD'ISteQS', first as warm (125 FL): primer solution" containing 20-40% byweight of: adhesive in. ethanol, and. second (immediately'there after) @513, volatile solvent-free'hot melt coating" applied at about 320 F.

Three different types ofrpolyamides-have been found useful in the adhesives of thisrinvention.

Polyamide A is described in Brubaker et .al; 2,285,009; Thisspolyamide is formed .by'reactingi hexamethylenediammonium adipate and h'exa'-=" methylenediammonium. sebacate with. caprolac tam oriwith G-amino-capmic .acid', oriby reacting if hexamethylenediammonium adipate, hexa'meth ylenediammoniumseb'acate, fi-amino-caprloic' acid, and. a mixture of hexam'ethylenediammo'enlum' suberate and. hexamethylenediammonium; azelate. I

Polyamide B is disclosed in a co-pen'ding 'ap' pli'cationof Cairns, Serial Number 539195;, filed June 7-, 1944, now Patent 2,430,860, granted November 18, 1947, and assigned-to. the assignee hereof. Thiswpolyamide isproduced by reacting a linear polyamide; having: an intrinsic viscosity of at least 0.4 and containing hydrogen-bearing:- amide groups as an integral part of the main polymer chain, with formaldehydeand. a formal-'- dehyde-reactive organic, compound having hydrogen'attached to an element of groups. V and: VI. of series 2 and 3 of the periodic table; partic ularlyan alcohol or a mercaptan, in thepresence of a catalyst.

The term intrinsic viscosity used'herein'is defined as logs-Kr" C in which it is the viscosity of *a dilute'solution (e. g., 0.5% concentration) of the'pol'ymerin" m-cresol divided by the viscosity of m-cresol in the same units and at the same temperature.

tially that obtained by using'approximately 40%.

diprimary, 20% primary-secondary, and 40 disecondary diamines in the preparation of the polyamide.

All three of these types of polyamides are characterized by being soluble to at least 15% in hot 80% ethanol, and by having a high degree of pliability.

Although thebookbinding adhesives of my invention may be produced by using any of the three types of polyamides described above, poly-' amide A is preferred.

term liquefying softener is used herein to describe the property possessed by certain softeners, or solvent plasticizers, of accelerating the normal melting rate of the special polyamides and lowering their fluid temperature to a practical level.

Thefollowing examples are given by way of illustration.

Example 1 Per cent by weight Coumarone indene-phenolic condensate (Nevillac TS) 35 Resorcinol (technical grade) 5 Polyamide A 60 The composition was prepared by charging the first portion into an oil-jacketed paddle mixer, heating to about 320 F., and slowly adding the polyamide'with agitation until a homogeneous hot melt solution was obtained.

An assembly of about 200 pages was tightly clamped between two parallel flat plates, with about inch of the binding edge of the assemblyexposed. After roughing the binding edges slightly with 'a sharp saw blade, 'a prime coat of a 30% solution by weightiof the composition of Example 1 in 80% ethanol heated to 125 F. was applied with a brush. The excess was immediately scraped off and the primed area allowed to dry for about threeseconds. A knife coating of the composition of Example 1 heated to 320 F. was applied immediately thereafter. The coatingwas'permitted to cool fora few seconds and the pressure means were then removed. The binding was already sufllciently strong for all ordinary handling, including trimming of the pages. After standing for two days, during which period the'plastic' melt set up to a hard film, the binding was exceptionally strong, as pages could only be removed by tearing the paper, there being no separation at the juncture of the edges of the pages and. the adhesive coating. The latter was tough and flexible and withstood repeated flexing and hard usage. The binding was completely waterproof, and remained unaffected in usefulness over the temperature'ra'nge of 0-150 F.

Example -2 This composition was prepared by mixing the ingredients'in an oil-jacketed paddle mixer and heating to about 160 C. with agitation until a homogeneous hot"=melt solution wfas "obtained. The hot melt-solution was-then applied to the binding edge of a book over a prime coat com- 1 prised of a 30% solution of the composition of Example 2 in.80%. ethanol in the same manner as described in Example 1. This binding was fully as tough and strong as that described above, but even more flexible and resilient. The binding was allowed to cool, and, in contrast to Example 1, after one or two minutes, it had reached its maximum strength.

Example 3 Per cent by weight Coumarone indene-phenolic condensate (Nevi1lac OA) 45 Polyamide o 55 This composition was prepared in a manner, similar to that of Example. 2 and applied as described in Example 1, again using a primer prepared as above from the composition under test. This binding was somewhat softer and more flexible than those described above, but otherwise equal in all respects.

This composition was prepared in a manner similar to that of Example 2 and applied on its individualprimer as described in the" previous. examples. This binding was very soft and flex-.

ible but still retained sufiicient toughness to per mit its use for binding periodicals and the like.

This composition wasprepared inafmanner similar to that of Example? and, applied over its individual primer as described in the previous examples. This binding set af ter 48 hours to. a remarkably tough and leathery state. Its shape-retaining characteristics were equal to Examples 1 and 2. W

-- Per cent by weight Octyl phenol 45 its individual primer-as described in the previous examples. A highly tough and resilient binding wasproduce'd which wassuitable for periodicals: and the like. g V f c i?"v Pages prepared as above; wherein the 'ge'nei ally unsatisfactory stapling method or the 'ex-' pensive, time-consumingstep of stitching is dis pensed with, may then be combined with a-'suit-' able cover to: forms book bar-"methods custom=-. ari-ly' employed; some. cases, prior't'o adding the outside cover, a fabric reinforcement is placed over'the film of adhesiveand embedded therein while the latter is hot and sufiiciently softened or tacky to be receptive and. adherent to thefabrie layer.

In commercial use, thepages may be assembled between fiat metal plates held together under pressure and adjusted to l'e'aveabout 1 s inchto inch of the edges exposed after they a're trimmed. The assembled pages are then passed through a-cutter to trim the edges, and then to roughers' to open up the fibers-at'the edges of the pages to make themmore receptive to the adhesive composition, so itwill slightly penetrate into the interstices. The edges are next brushed with rotating brushes to remove any loose fibers resulting from the roughing operation. The

edges'of the pages are'thenj coated'with a warmed 125' F.) liquid primer consisting of a solution of the hot melt adhesive in'80%'ethano1, the sur-' face excess removed with flexible scrapers, and

then the-hot melt itself is applied at about 320 F. by a conventional'revolving. applicator consisting of a fiat-surfaced wheel about one half' immersed in the hot melt composition. The thickness of the adhesive film applied is regulated by an adjustable scraper knife. If additional'reinforcement is desired, a sheet of fabric, such as cheesecloth, may be pressed into the surface of the applied adhesive film while the latter is still hot; The outside bookv cover is finally combined with the improved cemented book pages by con ventional means.

A modification of this process involves preheating the binding edges to a temperature higher than the adhesive application temperature, and

then immediately applying the hot melt-at 320.

The proportion of polyamide to compatible liquefying softener. is limited by the maximum viscosity of the melt, which must be held at about 320 F. (higher temperatures are quite possible butlat theexpense of pot stability), and by the minimum degree of toughness and tensile strength required at temperatures (-150'F.) in which a bookbinding adhesive might conceivably be used. The examples illustrate compositions formulated to give good application viscosities with excellent stability'at 320 F., as well as films of high tensile strength, toughness, and fiexibilityin the range of 0 1-'5'0 F. It is essentia1 that the ratio of polyamide 'to'softener be between 45:55 and 65:35. Ratios higher or lower v flexible and tough and will not deteriorate from. longexposure to air and variationsintempera ture. Due to the high degree of: fiexibilityrand'; elasticity of the new adhesive compositions, they vention. --"Ihis-film thickness-maybe conveniently obtained by applying theadhesive composition at about 200 to 500 poises viscosity. 'I 'his is obtained and controlled by heating thecompositionto proper temperature; for example, 320 i; for the compositions of the examples.

The invention is characterized by numerous.

valuable advantages. Of primary importance is the" elimination of-the time-consuming and ex pensive stitching operation for binding book.

pages. The new binding means is permanently will successfully withstand the severe'rounding and backing operations. required inthe manu- They' are; also; waterproof, and are unaffected. by exposures-to. Complicated: machinery and. highly skilled. labor. arenot required in the:

facture of hard bound books.

high humidity.

process of the present invention, thus contr'ib uting to theappreciable economieswhichmay be. realizedin the manufacture of theimproved book.

construction. Books, and like articlesv bound. by.

the new means are more generally durableland.

will withstand severe usage for, longer periods than books bound. by prior adhesive methods; Less manufacturing space is needed since, incontradistinction to earlier methods requiring stitching, there is no delay at any point in the. operational steps in the process.

It will be apparent that many widely different embodiments of this invention can bemade with-,

out departing from the spirit and, scope thereof.;. and, therefore, it is not. intendedto be limited except as. indicated in. the appendedclaims.

I claim: I

:12. A, solvent-free, hot melt adhesivecomposn. tion particularly adaptedfor bindingbooks, c,om-'

prisingv an ethanol-soluble synthetic linear polyamide having an intrinsic. viscosity of at least 0.4 and containing amide. groupsseparated by an average of at least two carbon atoms as anin,-. tegral..part of. the main polymer chain-.and a.

compatible liquefying softener therefor, thetratio. of .polyamide. to softenerbeing between. 45.155;

viscosity or room temperature toughness.

"The liquefying softeners disclosed above function primarily to cause rapid melting of the adhesive-composition to a mobile liquid state above about 265 F. without detracting greatly from the natural toughness and tensile strength of the polyamide resin film at room temperature.

Nonyl phenol, decyl phenol, diamyl phenol and other substituted phenols and related substances are also suitable for use as liquefying softeners for the polyamide hot melts of this invention.

For most purposes, about 3 mils to 10 mils film thickness of final adhesive film gives the superior binding properties provided in the present in- 2.'The composition of claim. 1, in whichnthe. p-olyamide is the reaction product of hexamethyl enediammonium adipate hexamethylenediam monium sebacate, and caprolactamlt 3. .The composition. of claim 1, in Whichthe polyamide is the reaction product of a linear polyamide, which has an intrinsic viscosity "of at vleast 0.4 and. contains hydrogen-bearing. amide groups as an integral part of the main. polymer chain, with formaldehyde and a formaldehydereactive organic compound having hydrogen attached to an element of groups V and VI of series 2 and 3 of the periodic table, in the presence of a catalyst. Y

:4. The composition of claim 1, inwhich-the polyamide is a polyhexamethyleneisebacamide in which 50% of the amide groups are alkylated by isobutyl groups and which is obtained from a mixture of approximately 40% diprimary, 20% primary-secondary, and 40% disecondary diamines.

5. The composition of claim 1, in which the liquefying softener is a coumaron indene-phenolic condensation product.

6. The composition of claim 1, in which the liquefying softener is comprised of 87 parts of improved binding.

viscosity-of at least 0.4,. and containing amide groupsseparated by. an average of at least two carboniatoms as an integral part of the main polymer chain and being soluble in 80% ethanol, a compatible liquefying softener, and a volatile solvent therefor, removing substantially all un--v absorbed coating, evaporating the volatile sol' vent, and applying at about 320 F. a solventfree,.. hotmelt adhesive to the primer coated edges of the paper, said adhesive comprising a synthetic linear polyamide having the same characteristics as that above and a compatible liquef yin'g softener, the ratio of polyamide to softener in both the primer composition and the hot melt adhesive'being between 45:55 and 65:35.

10. The process of claim 9 in which the poly.- amide is the reaction product of hexamethylenediammonium adipate, hexamethylenediammonium sebacate, and caprolactam.

'11. The process of claim 9, in which the lique fying softener is a coumarone indene-phenolic condensation product. I

12. A process for binding books Without stitching or stapling, which comprises clamping together under pressure, with a small portion" of the binding edges exposed, the pages which are to form a book, roughing the exposed binding edges, coating said binding edges with a warm primer composition, comprising a synthetic linear polyamide having an intrinsic viscosity of at least 0.4 and containing amide groups separated by an average of at least two carbon atoms as an integral part of the main polymer chainpand being soluble in 80% ethanol, a compatible liquefying softener, and a volatile solvent therefor,

removing substantially all unabsorbed coating, evaporating the volatile solvent, and applying at above 320F.a. solvent-free, hot melt adhesive to the primer coated edges of the paper, said adhesive comprising a synthetic linear polyamide having thev same characteristics as that above v and aicompatible liquefying softener, the ratio of polyamide'to softener in both the primer composition andthe hot melt adhesive being between 45:55land-65235. 13. A process for binding books without stitching or stapling, which comprises clamping together under pressure, with a small portion of the binding edges exposed, the pages which are to form a book, preheating the exposed binding edges, and applying at about 320 F. a solvent- 85 free, hot melt adhesive :i-to the exposed edges, saidfadhesive comprising a synthetic linear polyamide having an intrinsic viscosity of at least 0.4 and containing'amide groups separated by an average? of at leasttwo carbon atoms as an in tegral part of the main polymer chain and being soluble in 80% ethanol and a compatible liquefying softener therefor, the ratio, of polyamide to softener being between 45:55 and 65:35 and thetemperature of the: preheating treatment being higher than the hot-melt application temperature.

14. 'The process of claim-13, in which the poly-' amide is the reaction product of hexamethylenediammonium adipate, hexamethylenediammonium sebacate, and caprolactam.

15. An article of manufacture, having a plurality of pages bound together by a solvent-free, hot melt adhesive composition comprising a syn-];

thetic linear polyamidehaving an'intrinsic viscosity of at least 0.4,and containing amide-groups separated by anaverage of at least two carbon; atoms as an integral part of the main polymerchain and being soluble in 80% ethanol and a compatible liquefying softener for the said poly' amide, the ratio of polyamide to softener being between 45:55 and :35.

16. A book havingits pages embedded in amatrix of an adhesive and a cover firmly bonded thereto, the said adhesive being self-sumcientas the sole binding means and consisting of a substantially solvent-free, composition containing a synthetic linear polyamide having an intrinsic; viscosity of at least 0.4 and containing amide-- groups separated by an average/0f at leasttwo carbon atoms as an integral part of the main polymer chain, and beingsoluble in ethanol; and a compatible liquefying softener for the said polyamide, the ratio ofthe said-polyamide to the said liquefying-softener being within 'the range of'45to55 and 65 to 35. L p 1, j -R,ODNEY G; BROWN.

REFERENCES CITED Y The following references are of record in the file of this patent: M

UNITEns ra ns PATENTS U 'Da te Number Name '1 1' 254,105 .Redford Feb. 28, 1882 1,565,629 Egerton Dec. 15', 1925 1 ,804,392 Alger et a1. May 12, 1931 2,216,835 Carothers Oct. 8, 1940 2,265,119 Coolidge Dec. 2, 1941 2,311,537 Vaala v Feb. 16, 1943 2,324, 34 Gurwick July 20,1943 2,340,652 Dwyer Feb. 1, 1944 2,371,566 Williams Mar. 13, 1945 2,374,069 Balthis l Apr. 17, 19,45

f FOREIGN PATENTS Number Country .Date' 116,167 Australia 1. Aug. 10, 19.40

1 1 OTHERVRE/E'IERENCES v Chem. and Met. Eng, April I946, page 319. Y' 

1. A SOLVENT-FREE, HOT MELT ADHESIVE COMPOSITION PARTICULARLY ADAPTED FOR BINDING BOOKS, COMPRISING AN ETHANOL-SOLUBLE SYNTHETIC LINEAR POLYAMIDE HAVING AN INTRINSIC VISCOSITY OF AT LEAST 0.4 AND CONTAINING AMIDE GROUPS SEPARATED BY AN AVERAGE OF AT LEAST TWO CARBON ATOMS AS AN INTEGRAL PART OF THE MAIN POLYMER CHAIN AND A COMPATIBLE LIQUEFYING SOFTENER THEREFOR, THE RATIO OF POLYAMIDE TO SOFTENER BEING BETWEEN 45:55 AND 65:35.
 9. A PROCESS FOR BINDING BOOKS WITHOUT STITCHING OR STAPLING, WHICH COMPRISES CLAMPING TOGETHER UNDER PRESSURE, WITH A SMALL PORTION OF THE BINDING EDGES EXPOSED, THE PAGES WHICH ARE TO FORM A BOOK, COATING THE EXPOSED BINDING EDGES WITH A WARM PRIMER COMPOSITION COMPRISING A SYNTHETIC LINEAR POLYAMIDE HAVING AN INTRINSIC VISCOSITY OF AT LEAST 0.4 AND CONTAINING AMIDE GROUPS SEPARATED BY AN AVERAGE OF AT LEAST TWO CARBON ATOMS AS AN INTEGRAL PART OF THE MAIN POLYMER CHAIN AND BEING SOLUBLE IN 80% ETHANOL, A COMPATIBLE LIQUEFYING SOFTENER, AND A VOLATILE SOLVENT THEREFOR, REMOVING SUBSTANTIALLY ALL UNABSORBED COATING, EVAPORATING THE VOLATILE SOLVENT, AND APPLYING AT ABOUT 320* F. A SOLVENTFREE, HOT MELT ADHESIVE TO THE PRIMER COATED EDGES OF THE PAPER, SAID ADHESIVE COMPRISING A SYNTHETIC LINEAR POLYAMIDE HAVING THE SAME CHARACTERISTICS AS THAT ABOVE AND A COMPATIBLE LIQUEFYING SOFTENER, THE RATIO OF POLYAMIDE TO SOFTENER IN BOTH THE PRIMER COMPOSITION AND THE HOT MELT ADHESIVE BEING BETWEEN 45:55 AND 65:35.
 15. AN ARTICLE OF MANUFACTURE, HAVING A PLURALITY OF PAGES BOUND TOGETHER BY A SOLVENT-FREE HOT MELT ADHESIVE COMPOSITION COMPRISING A SYNTHETIC LINEAR POLYAMIDE HAVING AN INTRINSIC VISCOSITY OF AT LEAST 0.4 AND CONTAINING AMIDE GROUPS SEPARATED BY AN AVERAGE OF AT LEAST TWO CARBON ATOMS AS AN INTEGRAL PART OF THE MAIN POLYMER CHAIN AND BEING SOLUBLE IN 80% ETHANOL AND A COMPATIBLE LIQUEFYING SOFTENER FOR THE SAID POLYAMIDE, THE RATIO OF POLYAMIDE TO SOFTENER BEING BETWEEN 45:55 AND 65:35. 